“I can’t really be more British – I’m the deputy director of MI5,” she says, laughing.

She missed the television series the first time around.

It just happens that they were the clothes people wore when it was written.” Tentatively I broach the fact that, after the phenomenal success of Pride and Prejudice, one might have expected a steeper, or more consistent, career trajectory. I’ve only ever felt really fortunate that I seem to be able to go away, to be able to recede and come forward.” She didn’t act at all between 20.

“And there have been several years in which jobs were chosen because of the small number of days they would require me to go away. “Though I don’t feel like I am one completely because my oldest friend, Emily, and I were together a lot, and she even lived with us for six months at one point.

“I was young and easily made self-conscious, I suppose.

And I wanted to work in England, to play British people in Britain.” We debate whether one is exactly the same person in different accents and languages.

Next month she will be seen in Spooks: The Greater Good, the feature film of the MI5-set BBC series, which ran for nine years and 10 seasons until 2011, and made stars of Matthew Macfadyen, Keeley Hawes and Rupert Penry-Jones.

Ehle is based in upstate New York with her husband, the writer Michael Scott Ryan, and their son, 12, and daughter, six.

“There were a few days when I was having trouble finding words to express feelings of enthusiasm,” she says, laughing.

“But when I discovered ‘brilliant’, I was fine.” But when we sit down and I switch on my recorder, the atmosphere changes: suddenly she seems uncomfortable, answering questions with a diffident “I don’t know” and fixing her eyes on the floor for long periods.

One can probably assume Ehle is a fan of the espionage genre. Before Spooks is released she can be seen in A Little Chaos, a period piece directed by Alan Rickman (who also stars as Louis XIV) about the construction of the Palace of Versailles, with Kate Winslet and Matthias Schoenaerts. “I’m Louis XIV’s mistress who’s getting the boot and being nudged out,” she tells me. I explain that I wondered if she’d avoided costume drama so as not to be typecast. I can’t imagine wanting to avoid characters like her.

“Yes – you’re watching incredibly smart people who are dealing with information coming at them really fast and making decisions in high-stakes situations.” Did she speak directly to any former spooks? These non-disclosure things, how long do they last? Does it take a lot to get her into a corset these days? And anyway, I always thought of Pride and Prejudice as more of a romantic comedy than a period drama.